The present invention relates to determining specific geographic locations with respect to a centralized location. More specifically, the present invention relates to apparatus and methods by which a person or persons may quickly, and with sufficient accuracy, determine specific geographic locations within a relatively large area in a cost-effective and sufficiently accurate and efficient manner.
A variety of applications require accurate determination of point locations within a large area; one example is the locating of corner points for a property border. In the art of wide area lighting, one example is determining the location of support structures (many times poles) relative to an area of interest (e.g. sports field, parking lot). A primary concern is how to accurately map out point locations (e.g. within a certain distance and/or angular displacement tolerance) in a cost-efficient manner (e.g. with a limited number of persons utilizing economically viable equipment).
One way points are located over a large area is via use of tape measure. Open reel steel tape measures (e.g. model OTRS1810300E available from Keson Industries, Aurora, Ill., U.S.) may extend substantial distances, are portable, and are inexpensive. However, it is difficult to accurately map out an area using tape measures. Using again the example wide area lighting, assume a person is standing at an actual reference or location or what may also be called an origin point (e.g. home plate on a baseball field) and needs to measure out a distance both north and west of the origin point to place a pole. The tape measure must somehow be secured at the origin point (e.g. via stake or a second person holding the tape measure), stretched a certain distance north, that point marked, the tape measure moved to said point and staked (or otherwise secured), and then stretched a certain distance west. However, it is often unclear if the tape measure has been stretched in a straight line; user perception, wind conditions, and topography are a few factors that may affect the alignment of a tape measure. Thus, in this example, if the tape measure is misaligned as it is stretched north, the misalignment may be exacerbated as it is stretched west.
One attempted solution is to use multiple persons with multiple tapes measures, along with geometric principles and distinguishable site location features (e.g. foul line, second base), to ensure all lines are straight along the ground. As may be appreciated, however, this requires multiple trained personnel and is relatively slow. Additionally, limiting factors such as wind and other conditions still apply. Still further, if the area of interest (e.g. sports field, parking lot) is newly developed, distinguishing features (e.g. bases, parking stall lines) may not be available for reference.
While some of the aforementioned less complex methods to locate points over a large area in the current state of the art may be adequate for some applications, other applications may benefit from a higher degree of accuracy. For example, in the art of sports lighting, computer programs are often used to produce illumination summaries which detail precise pole locations about a field such that pre-aimed fixtures attached to said poles achieve a specified illumination level and light uniformity level on the field. Misalignment of even a single pole by several feet or more may diminish illumination and light uniformity levels beyond what is acceptable by governing codes.
One example of a high accuracy method of determining point locations over a large area is via use of land survey equipment such as laser transits (e.g. model DW092PK available from DeWALT Industrial Tool Company, Baltimore, Md., U.S.). While accurate, land survey equipment is generally costly, requires specially trained personnel to operate it, is relatively slow to operate, and requires regular calibration. An alternative method is to use handheld geographic position or location devices. While the ease of use and portability of such devices has increased in recent years, the cost and time required for operation remains high for applications requiring locating multiple points over a large area with a high degree of accuracy. Still another alternative is to use range finders (e.g. model TruPulse 200 available from Laser Technology, Inc., Centennial, Colo., U.S.) which are generally portable and quick to operate, but are also costly and are most useful when determining a distance or height from an origin to a known object (thus, useful to verify the distance from an origin point to an installed pole, but not particularly useful when verifying distance and direction from an origin or reference location to an unmarked location, as may be the case when installing the pole).
It may therefore be seen that apparatus and methods of determining point locations over a large area may benefit from improvements in ease of use, accuracy, speed of operation, cost-effectiveness, or any combination thereof.